Universally expanding cage

ABSTRACT

An expandable medical implant is provided with an implantable cage body. The proximal and distal ends of the cage body may each be provided with a tapered or cam portion. The implant may further include a proximal flexure, a distal flexure, a proximal plug member having a tapered portion configured to mate with the tapered portion of the proximal end of the cage body, and a distal plug member having a tapered portion configured to mate with the tapered portion of the distal end of the cage body. The proximal plug member may be configured to move longitudinally such that the distal flexure moves and the circumference of the proximal end of the cage body resiliently expands. The distal plug member may be configured to move longitudinally such that the proximal flexure moves and the circumference of the distal end of the cage body resiliently expands. Methods are also disclosed.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.14/939,905 filed Nov. 12, 2015 which claims the benefit of U.S.Provisional Application No. 62/078,850 filed Nov. 12, 2014.

INCORPORATION BY REFERENCE

All publications and patent applications mentioned in this specificationare herein incorporated by reference in their entirety to the sameextent as if each individual publication or patent application wasspecifically and individually indicated to be incorporated by reference.

FIELD

The present disclosure generally relates to medical devices forstabilizing the vertebral motion segment or other bone segments. Moreparticularly, the field of the disclosure relates to a universallyexpanding cage (UEC) and method of use for providing controlled spinalcorrection or other bond segment spacing and/or alignment.

BACKGROUND

Conventional spine cages or implants are typically characterized by akidney bean-shaped body comprising a hydroxyapatite-coated surfaceprovided on the exterior surface for contact with adjacent vertebralsegments or endplates which are shown in FIG. 1. A conventional spinecage with flat endplates is typically inserted posterolaterallyproximate to the neuroforamen of the distracted spine after a trialimplant creates a pathway. Optionally two parallel externally threadedconduits are inserted anteriorly to achieve lumbar arthrodesis. Theimplants are often of constant diameter whereas the L5-S1 disc space istrapezoidal, thus a ‘flat back’ syndrome may be iatrogenically created.Generally spine intradiscal implants are for lumbar fusion or cervicalmotion preservation, while a separate system of rods and screws correctsalignment.

With the novel UECs disclosed herein, additional options include fusionthroughout the spinal column, and deformity angular correction.

Existing devices for interbody stabilization have important andsignificant limitations. Among the limitations are an inability toexpand and distract the endplates. Consequently, if a cage that is “tosmall” is inserted it can ‘rattle around and never heal’. If the staticcage is too big, it can injure adjacent nerves or destabilize the spinevia end plate resection or subsidence.

Current devices for interbody stabilization include static spacerscomposed of titanium, PEEK, and high performance thermoplastic polymerproduced by VICTREX, (Victrex USA Inc, 3A Caledon Court, Greenville,S.C. 29615), carbon fiber, or resorbable polymers. Current interbodyspacers may not maintain interbody lordosis and can contribute to theformation of a straight or even kyphotic segments and the clinicalproblem of “flatback syndrome.” Separation of the endplates increasesspace available for the neural elements, specifically the neuralforamen. Existing static cages do not reliably improve space for theneural elements. Therefore, what is needed is an expanding cage thatwill increase space for the neural elements posteriorly between thevertebral bodies, or at least maintain the natural bone contours toavoid neuropraxia (nerve stretch) or encroachment.

U.S. Pat. No. 7,985,256, filed Sep. 26, 2006 and titled “SelectivelyExpanding Spine Cage, Hydraulically Controllable in Three Dimensions forEnhanced Spinal Fusion”, and U.S. Pat. No. 7,819,921, filed Oct. 31,2007 and titled “Linearly expanding spine cage for enhanced spinalfusion”, both provide detailed background on expanding spine cages.

The cages disclosed in U.S. Pat. No. 7,985,256 above are restricted touse with hydraulics, and lumbar fusion. The cage disclosed in U.S. Pat.No. 7,819,921 allows for trapezoidal linear expanding, not uniformexpansion, thus a trapezoidal L5 cage as disclosed therein will preservenatural lumbar lordosis. The disclosed cage was never developed. It isintended for use as two (2) parallel linearly expanding split conduitsinserted anteriorly for lumbar fusion.

In contrast, the UEC cages disclosed herein expands either uniformly, orat either end proximally or distally. Given the adjustment option thesurgeon can correct angulation deformity with the novel UEC.

Another problem with conventional devices of interbody stabilizationincludes poor interface between bone and biomaterial. Conventionalstatic interbody spacers form a weak interface between bone andbiomaterial. Although the surface of such implants is typically providedwith a series of ridges or coated with hydroxyapetite, the ridges may bein parallel with applied horizontal vectors or side-to-side motion. Thatis, the ridges or coatings offer little resistance to movement appliedto either side of the endplates. Thus, nonunion is common in allograft,titanium and polymer spacers, due to motion between the implant and hostbone. Conventional devices typically do not expand between adjacentvertebrae. Since the UEC expands under surgeon control, the visible,palpable ‘goodness of fit’ setting can ideal lock opposing vertebralendplates at the time of surgery. As healing accrues, the implantsbecome inert. Since no motion equates with no pain, clinical results areimproved with UECs.

Therefore, what is needed is a way to expand an implant to developimmediate fixation forces that can exceed the ultimate strength athealing, with improved abilities to enable disc space fixationsolidarity while correcting spine angular deformity. Such an expandableimplant ideally will maximize stability of the interface and enhancestable fixation. The immediate fixation of such an expandable interbodyimplant advantageously will provide stability that is similar to thatachieved at the time of healing. Such an implant will have valuableimplications enhancing early post-operative rehabilitation for thepatient.

Another problem of conventional interbody spacers is their largediameter requiring wide exposure. Existing devices used for interbodyspacers include structural allograft, threaded cages, cylindrical cages,and boomerang-shaped cages. Conventional devices have significantlimitation with regard to safety and efficacy. Regarding safety of theinterbody spacers, injury to neural and aortic elements may occur withplacement from an anterior or posterior approach. A conventional spinecage lacks the ability to expand, diminishing its fixation capabilities.Prior attempts to preserve lumbar motion have failed by extrusion of theimplant after implantation. The risks to neural elements are primarilydue to the disparity between the large size of the cage required toadequately support the interbody space, and the small space availablefor insertion of the device, especially when placed from a posterior ortransforaminal approach. Existing boomerang cages are shaped like apartially flattened kidney bean. Their implantation requires a wideexposure and potential compromise of vascular and neural structures,both because of their inability to enter small and become larger, anddue to the fact that their insertion requires mechanical manipulationduring insertion and expanding of the implant. Once current boomerangimplants are prepared for insertion via a trial spacer to make a pathwaytoward the anterior spinal column, the existing static cage is shovedtoward the end point with the hope that it will reach a desired anatomicdestination. Given the proximity of nerve roots and vascular structuresto the insertion site, and the solid, relatively large size ofconventional devices, such constraints predispose a patient to foraminal(nerve passage site) encroachment, and possible neural and vascularinjury.

Therefore, what is needed is a minimally invasive expanding spine cagethat is capable of insertion with minimal invasion into a smalleraperture. Such a minimally invasive spine cage advantageously could beexpanded with completely positional control or adjustment in threedimensions. What is also needed is a smaller expanding spine cage thatis easier to operatively insert into a patient with minimal surgicaltrauma in contrast to conventional, relatively large devices that createthe needless trauma to nerve roots in the confined space of thevertebral region. Existing interbody implants have limited spaceavailable for bone graft. Adequate bone graft or bone graft substituteis critical for a solid interbody arthrodesis. It would be desirable toprovide an expandable interbody cage that will permit a large volume ofbone graft material to be placed within the cage and around it, to fillthe intervertebral space. Additionally, conventional interbody implantslack the ability to stabilize endplates completely and prevent them frommoving. Therefore, what is also needed is an expanding spine cagewherein the vertebral end plates are subject to forces that bothdistract them apart, and hold them from moving. Such an interbody cagewould be capable of stabilization of the motion segment, therebyreducing micromotion, and discouraging pseudoarthrosis (incompletefusion) and pain.

Ideally, what is needed is a spine cage or implant that is capable ofincreasing its expansion in height and angle, spreading to a calculateddegree. Furthermore, what is needed is a spine cage that can adjust theamount of not only overall anterior posterior expansion, but also medialand lateral variable expansion so that both the normal lordotic curve ismaintained, and adjustments can be made for scoliosis or bone defects.Such a spine cage or implant would permit restoration of normal spinalalignment after surgery and hold the spine segments together rigidly,mechanically, until healing occurs.

What is also needed is an expanding cage or implant that is capable ofholding the vertebral or joint sections with increased pullout strengthto minimize the chance of implant fixation loss during the period whenthe implant is becoming incorporated into the arthrodesis bone block.

SUMMARY OF THE DISCLOSURE

According to some aspects of the disclosure, an expandable medicalimplant is provided with an implantable cage body having a proximal endand a distal end. In some embodiments, the proximal and distal ends ofthe cage body are each provided with a tapered or cam portion. The cagebody further has a longitudinal axis extending between the proximal endand the distal end of the cage body. The implant may further comprise atleast one proximal flexure at least partially located adjacent to theproximal end of the cage body and configured to allow a circumference ofthe distal end of the cage body to resiliently expand. The implant mayfurther comprise at least one distal flexure at least partially locatedadjacent to the distal end of the cage body and configured to allow acircumference of the proximal end of the cage body to resilientlyexpand. The implant may further comprise a proximal plug member having atapered portion configured to mate with the tapered portion of theproximal end of the cage body. The proximal plug member may beconfigured to move longitudinally relative to the cage body from a firstposition to a second position such that the at least one distal flexuremoves and the circumference of the proximal end of the cage bodyresiliently expands. The proximal plug member may also be configured tomove from the second position to the first position such that thecircumference of the proximal end resiliently contracts. The implant mayfurther comprise a distal plug member having a tapered portionconfigured to mate with the tapered portion of the distal end of thecage body. The distal plug member may be configured to movelongitudinally relative to the cage body from a third position to afourth position such that the at least one proximal flexure moves andthe circumference of the distal end of the cage body resilientlyexpands. The distal plug member may also be configured to move from thefourth position to the third position such that the circumference of thedistal end resiliently contracts.

In some embodiments, the cage body further comprises a first taperedbore at the proximal end configured to slidably receive the proximalplug member, and a second tapered bore at the distal end configured toslidably receive the distal plug member. The first tapered bore maythreadably engage the proximal plug member such that when the proximalplug member is rotated relative to the cage body, the proximal plugmember advances in a longitudinal direction relative to the cage body.The second tapered bore may threadably engage the distal plug membersuch that when the distal plug member is rotated relative to the cagebody, the distal plug member advances in a longitudinal directionrelative to the cage body.

In some embodiments, the at least one proximal flexure comprises agenerally circular and open ended aperture and a pair of generallyflexible beam portions extending longitudinally from the aperture. Theat least one proximal flexure may include a pair of longitudinallyextending beam portions separated by a longitudinally extending gap,wherein the at least one proximal flexure further comprises a connectorportion interconnecting proximal ends of the beam portions. The at leastone proximal flexure may include a plurality of circumferentially spacedproximal flexures, and the at least one distal flexure may include aplurality of circumferentially spaced distal flexures. The plurality ofproximal flexures may be rotationally staggered from the plurality ofdistal flexures.

In some embodiments, each of the proximal flexures includes a pair oflongitudinally extending beam portions separated by a longitudinallyextending gap and bridged together by a connector portioninterconnecting only proximal ends of the beam portions. Each of thedistal flexures may include a pair of longitudinally extending beamportions separated by a longitudinally extending gap and bridgedtogether by a connector portion interconnecting only distal ends of thebeam portions. Each of the proximal flexures can share a beam portionwith two of the distal flexures that are adjacent to each proximalflexure, thereby forming a continuous serpentine pattern along the cagebody.

In some embodiments, the implant includes a first adjustment membercoupled to at least the proximal plug member such that when the firstadjustment member is rotated, the proximal plug member is caused to movelongitudinally. The implant may further include a second adjustmentmember coupled to the distal plug member such that when the secondadjustment member is rotated, the distal plug member is caused to movelongitudinally, thereby allowing the proximal and the distal ends of thecage body to be expanded and contracted independent from one another.The first and the second adjustment members may be coaxially nested onewithin the other and independently rotatable. In some embodiments, thefirst and the second adjustment members each have knobs axially spacedbut adjacent to one another such that the knobs may alternately berotated in unison or individually. At least one of the first and thesecond adjustment members may have a keyed end configured to slidablymate and rotationally couple with its associated plug member such thatthe at least one adjustment member can be removed from the expandablemedical implant.

In some embodiments, the cage body has a square or circularcross-section transverse to the longitudinal axis.

In some embodiments, an expandable medical implant includes animplantable cage, a plurality of proximal flexures, a plurality ofdistal flexures, a proximal plug member, a distal plug member, and firstand second adjustment members. In these embodiments, the implantablecage body has a proximal end and a distal end each provided with athreaded and tapered bore. The cage body has a longitudinal axisextending between the proximal end and the distal end of the cage body.The plurality of proximal flexures are circumferentially spaced and eachis at least partially located adjacent to the proximal end of the cagebody and configured to allow a circumference of the distal end of thecage body to resiliently expand. Each of the proximal flexures comprisesa pair of longitudinally extending beam portions separated by alongitudinally extending gap and bridged together by a connector portioninterconnecting only proximal ends of the beam portions. The pluralityof distal flexures are circumferentially spaced and each is at leastpartially located adjacent to the distal end of the cage body andconfigured to allow a circumference of the proximal end of the cage bodyto resiliently expand. Each of the distal flexures comprises a pair oflongitudinally extending beam portions separated by a longitudinallyextending gap and bridged together by a connector portioninterconnecting only distal ends of the beam portions. Each of theproximal flexures shares a beam portion with two of the distal flexuresthat are adjacent to each proximal flexure, thereby forming a continuousserpentine pattern along the cage body. The proximal plug member has athreaded and tapered circumference configured to mate with the threadedand tapered bore of the proximal end of the cage body. The proximal plugmember is configured to move along the longitudinal axis relative to thecage body from a first position to a second position such that theplurality of distal flexures move and the circumference of the proximalend of the cage body resiliently expands. The proximal plug member isalso configured to move from the second position to the first positionsuch that the circumference of the proximal end resiliently contracts.The distal plug member has a threaded and tapered circumferenceconfigured to mate with the threaded and tapered bore of the distal endof the cage body. The distal plug member is configured to move along thelongitudinal axis relative to the cage body from a third position to afourth position such that the plurality of proximal flexures move andthe circumference of the distal end of the cage body resilientlyexpands. The distal plug member is also configured to move from thefourth position to the third position such that the circumference of thedistal end resiliently contracts. The first adjustment member isrotationally coupled to the proximal plug member such that when thefirst adjustment member is rotated, the proximal plug member is causedto move along the longitudinal axis. The second adjustment memberrotationally coupled to the distal plug member such that when the secondadjustment member is rotated, the distal plug member is caused to movelongitudinally, thereby allowing the proximal and the distal ends of thecage body to be expanded and contracted independent from one another.The first and the second adjustment members are coaxially nested onewithin the other and independently rotatable. The first and the secondadjustment members each have knobs axially spaced but adjacent to oneanother such that the knobs may alternately be rotated in unison orindividually. At least one of the first and the second adjustmentmembers may have a keyed end configured to slidably mate androtationally couple with its associated plug member such that the atleast one adjustment member can be removed from the expandable medicalimplant.

According to some aspects of the disclosure, a method of distractingadjacent bone segments having opposing surfaces is provided. The methodcomprises the steps of inserting an expandable medical implant asdescribed above between the opposing surfaces of the bone segments, andmoving the proximal and the distal plug members longitudinally andindependently from one another such that the proximal and the distalends of the cage body expand independently to alter the distance and theangle between the opposing surfaces of the bone segments. In someembodiments, the method further includes the step of removing at leastone adjustment member from the medical implant after the adjustmentmember has been used to move at least one of the proximal and distalplug members. In some embodiments, the bone segments are adjacentvertebrae, and the opposing surfaces are end plates of the adjacentvertebrae.

BRIEF DESCRIPTION OF THE DRAWINGS

For the purpose of illustrating concepts of the disclosure, the drawingsshow aspects of one or more embodiments. However, it should beunderstood that the present disclosure is not limited to the precisearrangements and instrumentalities shown in the drawings, wherein:

FIGS. 1-3 are a series of lateral representations of two vertebralbodies, wherein FIG. 1 depicts the insertion of an exemplary UniversallyExpanding Cage (UEC) in its unexpanded state, FIG. 2 depicts the UEC inplace between the vertebral bodies and still in its unexpanded state,and FIG. 3 depicts the inserted UEC in its expanded state.

FIG. 4 is a perspective view of a first embodiment of a UEC in anunexpanded state according to aspects of the disclosure.

FIG. 5 is an exploded perspective view showing the UEC of FIG. 4.

FIG. 6 is a perspective view showing the cage body of the UEC of FIG. 4.

FIG. 7 is a proximal end view of the UEC of FIG. 4.

FIG. 8 is a side view of the UEC of FIG. 4.

FIG. 9 is a side cross-sectional view of the UEC of FIG. 4.

FIG. 10 is a perspective view of a second embodiment of a UEC in anunexpanded state according to aspects of the disclosure.

FIG. 11 is an exploded perspective view showing the UEC of FIG. 10.

FIG. 12 is a side view showing the UEC of FIG. 10.

FIG. 13 is a proximal end view showing the UEC of FIG. 10.

FIG. 14 is a distal end view showing the UEC of FIG. 10.

FIG. 15 is a side cross-sectional view showing the UEC of FIG. 10.

FIG. 16 is a perspective view of a third embodiment of a UEC in anunexpanded state according to aspects of the disclosure.

FIG. 17 is an exploded perspective view showing the UEC of FIG. 16.

FIG. 18 is a side view showing the UEC of FIG. 16.

FIG. 19A is a side cross-sectional view showing the UEC of FIG. 16.

FIG. 19B is an end cross-sectional view showing the UEC of FIG. 16.

FIGS. 20A-20C are a series of side views showing the progressiveexpansion of the UEC of FIG. 16, wherein FIG. 20A shows both ends of theUEC in the unexpanded state, FIG. 20B shows only one end expanded, andFIG. 20C shows both ends expanded.

FIG. 21 is a perspective view of a fourth embodiment of a UEC in anunexpanded state according to aspects of the disclosure.

FIG. 22 is a perspective view of a fifth embodiment of a UEC in anunexpanded state according to aspects of the disclosure.

FIG. 23 is a distal end view showing the UEC of FIG. 22.

FIG. 24 is a side view showing the UEC of FIG. 22.

FIG. 25 is a side cross-sectional view showing the UEC of FIG. 22.

FIG. 26 is a cranial to caudal view showing the insertion sites of dualUECs on a vertebral body in one example implementation.

FIG. 27 is an oblique posterolateral view showing one of the insertionsites of the implementation of FIG. 26.

FIG. 28 is an oblique posterolateral view showing the axes of adjustmentprovided by the implementation of FIG. 26.

FIG. 29 is an oblique anterior view showing an anterior column implant.

FIG. 30 is a posterior view showing a human spine exhibiting scoliosis.

FIG. 31 is a posterior view showing the spine of FIG. 29 after beingcorrected according to aspects of the disclosure.

FIGS. 32A-32C are anterior, lateral and oblique views, respectively,showing adjacent vertebral bodies having misalignments/uneven spacing.

FIGS. 33A-33C are anterior, lateral and oblique views, respectively,showing the vertebral bodies of FIGS. 32A-32C with themisalignments/uneven spacing corrected according to aspects of thedisclosure.

DETAILED DESCRIPTION

Referring to FIG. 1-3, a series of lateral views of vertebral segments50 and 52 are shown, depicting the insertion and expansion of oneembodiment of UEC (Universally Expanding Cage). The depicted vertebralbodies 50 and 52 have an average 8 mm gap between vertebral end plates,representing an average intervertebral space 54. In a typicalimplementation, a complete discectomy is performed prior to theinsertion of the UEC 56. The intervertebral disc occupying space 54 isremoved using standard techniques including rongeur, curettage, andendplate preparation to bleeding subcondral bone. The posteriorlongitudinal ligament is divided to permit expansion of theintervertebral space.

The intervertebral space 54 may be distracted to about 10 mm using arotating spatula (not shown). This is a well-known device that lookslike a wide screw driver that can be placed into the disc spacehorizontally and turned 90 degrees to separate the endplates. A novelfeature of the UEC is that after intervertebral disc space expansion andpreparation (by curetting or ideally arthroscopically facilitated discmaterial removal), the UEC implant per se can be inserted through anyorifice or angle that does not cause injury to nerves or otherstructures, positioned at the immediate implant location and consequentexpansion platform to yield both the best fusion and angular correctionresults.

In the example implementation depicted in FIGS. 1-3, UEC 56 is insertedposteriorly (in the direction of arrow 58) between vertebral bodies 50and 52, as shown in FIG. 1. The vertebral space 54 depicted is meant torepresent any vertebral space in which it is desired to insert the UEC(sacral, lumbar, thoracic and/or cervical), and from any directionpermitted by the surrounding anatomy. In accordance with an aspect ofthe disclosure, the UEC is reduced to a small size in its unexpandedstate to enable it to be inserted through into the intervertebral space54 as shown in FIG. 1. FIG. 2 shows UEC 56 inserted between vertebralbodies 50 and 52, with UEC 56 still in its unexpanded state. In oneexemplary embodiment, dimensions of an unexpanded UEC are: 10-12 mmwide, 10 mm high and 28 mm long to facilitate insertion and therebyminimize trauma to the patient and risk of injury to nerve roots. Thesedimensions may accommodate the flat external surfaces. Once in place,the exemplary UEC 56 may be expanded to 140 percent of its unexpandedsize (as shown in FIG. 3), enabling 20 degrees or more of spinalcorrection depending on the 3D clinical pre-operation anatomic analysis.

It should be noted that while the exemplary UEC 56 depicted in FIGS. 1-3is an implant intended to ideally fill the warranted space, other shapesof implants such as those shown in later figures and/or described hereinmay be used. In various embodiments, the implants may have a transversecross-section that is circular, oval, elliptical, square, rectangular,trapezoidal, or other shape suited to fill the implant site and transmitthe required loads. The implants may straight, curved, bean-shaped,and/or include other shapes and aspect ratios. Additionally, theexternal surfaces may be smooth, spiked, threaded, coated and/or furtheradapted as subsequently described in more detail. The UEC can be used atany spinal level the surgeon deems in need of fusion, and may be placedat any position and angle relative to the vertebral endplates as may beneeded. One, two, or more UECs may be placed at any particular level toachieve the desired height and angles between vertebral bodies. As willbe later described, multiple UECs may be used to adjust the overallcranio-caudal height, the anterior-posterior angle, and themedio-lateral angle between adjacent vertebral bodies. UECs may beimplanted at multiple levels to obtain or restore the desired threedimensional curvature and positioning of the spine.

Referring to FIGS. 4-9, a first embodiment of an exemplary UEC 100according to aspects of the disclosure is shown. FIG. 4 is an enlargedperspective view which shows details of UEC 100. For ease ofunderstanding, a proximal end 104 and a distal end 106 of UEC 100 can bedefined as shown in FIG. 4. It should be noted that while the distal end106 of UEC 100 is typically inserted first into a patient and proximalend 104 is typically closest to the surgeon, other orientations of thisexemplary device and other devices described herein may be adopted incertain procedures despite the distal and proximal nomenclature beingused.

Referring to FIG. 5, an exploded perspective view shows the individualcomponents of UEC 100. In this first embodiment, UEC 100 includes acylindrically-shaped cage body 108, a proximal plug 110, a distal plug112, a threaded actuator 114, and a washer 116. The terms “plug” and“plug member” are used interchangeably herein. Actuator 114 has a shanksized to slidably pass through a central bore within proximal plug 110when UEC 100 is assembled. Actuator 114 also has threads on its distalend for engaging with a threaded central bore within distal plug 112.Proximal plug 110 and distal plug 112 each have outer surfaces that areinwardly tapered to match inwardly tapered surfaces within cage body 108(as best seen in FIG. 9) With this arrangement, actuator 114 may berotated in a first direction to draw distal plug 112 toward proximalplug 110 to outwardly expand cage body 108, as will be subsequentlydescribed in more detail.

Referring to FIG. 6, this perspective view shows details of cage body108 of the first exemplary embodiment of UEC 100. In this embodiment,cage body 108 includes eight longitudinally extending beam portions 118,each separated from an adjacent beam portion 118 by a longitudinallyextending gap 120. In other embodiments (not shown), the cage body mayinclude fewer or more than eight beam portions, and/or beam portionshaving a different or varying cross-section or shape. Cage body 108 ofthe current embodiment also includes eight circumferentially extendingconnector portions 122. The connector portions 122 interconnect the endsof the beam portions 118. Four of the connector portions 122 are locatedat the proximal end 104 of cage body 108, and the other four connectorportions 122 are located at the distal end 106. The connector portions122 located at the proximal end 104 are staggered in relation to theconnector portions 122 located at the distal end 106 such that each pairof adjacent beam portions 118 are connected at only one end by aconnector portion 122. With this arrangement the beam portions 118 andconnector portions 122 form a continuous serpentine or repeatingS-shaped pattern. The beam portions 118 and or the connector portions122 are configured to resiliently flex to allow the cage body 108 toincrease in diameter when urged radially outward by plugs 110 and 112(shown in FIG. 4). When plugs 110 and 112 are not urging cage body 108radially outward, the resiliency of beam portions 118 and or connectorportions 122 allows cage body 108 to return to its original reduceddiameter. It can be appreciated that as beam portions 118 and orconnector portions 122 flex outwardly, gaps 120 become wider at theiropen ends opposite connector portions 122. The outwardly facing surfacesof beam portions 118 may each be provided with one or more points orspikes 123 as shown, to permit cage body 108 to grip the end plates ofthe vertebral bodies.

Referring to FIG. 7, an end view of the proximal end 104 of UEC 100 isshown. The enlarged head at the proximal end of actuator 114 may beprovided with a recessed socket 124 as shown for removably receiving atool for turning actuator 114. Proximal plug 110 (and distal plug 112,not shown) may be provided with radially outwardly extendingprotuberances 126 that reside in one or more gaps 120 and abut againstthe side of beam portions 118. This arrangement prevents plugs 110 and112 from rotating when actuator 114 is turned, thereby constrainingplugs 110 and 112 to only move axially toward or away from each other.Proximal plug 110 (and distal plug 112) may be provided with throughholes and or recesses 128 to allow for bony ingrowth from the vertebralbodies for more solidly healing/fusing UEC 100 in place. Longitudinallyextending slots 130 (shown in FIG. 4) may also be provided for thispurpose, and or for packing plugs 110 and 112 with autograft, allograft,and/or other materials for promoting healing/fusion.

Referring to FIGS. 8 and 9, a side view and side cross-sectional view,respectively, are shown. In operation, UEC 100 is expanded by insertinga tool such as a hex key wrench or driver (not shown) into the recessedsocket 124 at the proximal end of actuator 114 and turning it clockwise.As best seen in FIG. 9, the distal end of actuator 114 is threaded intothe central bore of distal plug 112. Turning actuator 114 clockwisecauses the distal end of actuator 114 to pull distal plug 112 towardsthe center of cage body 108 while the enlarged head at the proximal andof actuator 114 pushes proximal plug 110 towards the center. Thismovement in turn causes the ramped surfaces 132 of plugs 110 and 112 toslide inwardly along the ramped surfaces 134 located along the inside ofbeam portions 118 and connector portions 122 to cause these elements toflex and expand radially outward as previously described. This processmay be reversed by turning actuator 114 counterclockwise. The resilientinward forces from the beam portions 118 and or connector portions 122(and or the compressive forces from adjacent vertebral bodies) againstplugs 110 and 112 causes the two plugs to separate axially, therebyallowing UEC 100 to return to its non-expanded state.

Referring to FIGS. 10-15, a second embodiment of an exemplary UEC 200according to aspects of the disclosure is shown. FIG. 10 is aperspective view which shows details of UEC 200. UEC 200 includes aproximal end 204 and a distal end 206, and shares many of the samefeatures of previously described UEC 100, which are identified withsimilar reference numerals.

Referring to FIG. 11, an exploded perspective view shows the individualcomponents of UEC 200. In this second embodiment, UEC 200 includes anelongated cylindrical cage body 208, a proximal plug 210, and a distalplug 212. Distal plug 212 includes an integrally formed actuator rod 214that extends along the internal central axis of cage body 208 towardsproximal plug 210 when UEC 200 is assembled. Proximal plug 210 anddistal plug 212 each have outer surfaces that are threaded and inwardlytapered to match threaded and inwardly tapered surfaces within cage body208 (as best seen in FIG. 15). With this arrangement, each plug 210 and212 may be independently rotated to move the particular plug axiallytoward the middle of cage body 208 to outwardly expand that particularend 204 or 206 of cage body 208, as will be subsequently described inmore detail.

As shown in FIGS. 11 and 12, cage body 208 includes eight longitudinallyextending beam portions 218, each separated from an adjacent beamportion 218 by a longitudinally extending gap 220. In other embodiments(not shown), the cage body may include fewer or more than eight beamportions, and/or beam portions having a different or varyingcross-section or shape. Cage body 208 of the current embodiment alsoincludes eight circumferentially extending connector portions 222. Theconnector portions 222 interconnect the ends of the beam portions 218.Four of the connector portions 222 are located at the proximal end 204of cage body 208, and the other four connector portions 222 are locatedat the distal end 206. The connector portions 222 located at theproximal end 204 are staggered in relation to the connector portions 222located at the distal end 206 such that each pair of adjacent beamportions 218 are connected at only one end by a connector portion 222.With this arrangement the beam portions 218 and connector portions 222form a continuous serpentine or repeating S-shaped pattern. The beamportions 218 and or the connector portions 222 are configured toresiliently flex to allow the cage body 208 to increase in diameter whenurged radially outward by plugs 210 and 212. When plugs 210 and 212 arenot urging cage body 208 radially outward, the resiliency of beamportions 218 and or connector portions 222 allows cage body 208 toreturn to its original reduced diameter. It can be appreciated that asbeam portions 218 and or connector portions 222 flex outwardly, gaps 220become wider at their open ends opposite connector portions 222. Theoutwardly facing surfaces of beam portions 218 may each be provided withone or more points or spikes 223 as shown, to permit cage body 208 togrip the end plates of the vertebral bodies.

Referring to FIG. 13, an end view of the proximal end 204 of UEC 200 isshown. The proximal plug 210 may be provided with a recessed socket 224as shown for removably receiving a tool for turning proximal plug 210 ineither direction, such as a five-lobed driver (not shown).Alternatively, other suitable types of recessed sockets, slots,protruding and/or keyed features may be utilized with a mating driver.The proximal end of actuator shaft 214 (which extends proximally fromdistal plug 212 inside cage body 208) may be accessed through a centralbore 225 in proximal plug 210. The proximal end of actuator shaft 214may be shaped as shown to be received within a mating driver socket(such as a five-lobed socket, not shown), which can be removablyextended into the center of cage body 208 through central bore 225. Withthis arrangement, both the proximal plug 210 and the distal plug 212 canbe independently accessed and rotated from the proximal end of UEC 200so that the proximal end 204 and the distal end 206 of UEC 200 can beexpanded or contracted independently.

Referring to FIG. 14, an end view of the distal end 206 of UEC 200 isshown. By comparing FIGS. 13 and 14, it can be appreciated thatconnector portions 222 at the proximal end 204 of UEC 200 are staggered(i.e. rotated 45°) in relation to the connector portions 222 at thedistal end 206 of UEC 200.

Referring to FIG. 15, a side cross-sectional view of UEC 200 is shown.In operation, the proximal end 204 of UEC 200 may be independentlyexpanded by inserting a tool such as a five-lobed driver (not shown)into the recessed socket 224 of proximal plug 210 and turning itclockwise. Turning proximal plug 210 clockwise causes the threadedramped surfaces 232 of plug 210 to translate inwardly (to the right inFIG. 15) along the threaded ramped surfaces 234 located along the insideof beam portions 218 and connector portions 222 to cause these elementsto flex and expand radially outward as previously described. Thisprocess may be reversed by turning proximal plug 210 counterclockwise,thereby allowing the proximal end 204 of UEC 200 to return to itsnon-expanded state. Similarly, the distal end 206 of UEC 200 may beindependently expanded by inserting a tool such as a five-lobed socket(not shown) through the central bore 225 in proximal plug 210 until itengages with the proximal end of actuator 214, which is attached todistal plug 212. Turning distal plug 212 counterclockwise (from theperspective of the proximal end) causes the threaded ramped surfaces 232of plug 212 to translate inwardly (to the left in FIG. 15) along thethreaded ramped surfaces 234 located along the inside of beam portions218 and connector portions 222 to cause these elements to flex andexpand radially outward as previously described. This process may bereversed by turning distal plug 212 clockwise, thereby allowing thedistal end 206 of UEC 200 to return to its non-expanded state.

The adjustment tools described above (not shown) for turning proximalplug 210 and distal plug 212 may be inserted one at a time into UEC 200.Alternatively, the two tools may be nested together, with the tool forturning the distal plug 212 passing through a central bore in the toolfor turning the proximal plug, as will be subsequently shown anddescribed in relation to other embodiments. With this arrangement, bothtools may be turned simultaneously or individually. In some embodiments,both proximal plug 210 and distal plug 212 are provided withright-handed threads, so that when both tools are simultaneously turnedin the same direction, one end of UEC 200 expands while the other endcontracts, thereby changing the outer surface angle of UEC 200 withoutsubstantially changing its overall diameter (i.e. without substantiallychanging the diameter or height of the midpoint of UEC 200.) Forexample, by turning the two tools in the same direction, the lordoticangle between two vertebral bodies can be changed by UEC 200 withoutsubstantially changing the height between the two vertebral bodies.

In other embodiments, one of the plugs 210 or 212 may be provides with aright-handed thread and the other plug provided with a left-handedthread. In these embodiments, when both adjustment tools aresimultaneously turned in the same direction, both ends 204 and 206 ofUEC 200 expand or contact together without substantially changing theouter surface angle of UEC 200. For example, by turning the two tools inthe same direction, the height between the two vertebral bodies can bechanged by UEC 200 without substantially changing the lordotic anglebetween two vertebral bodies.

In some embodiments, plugs 210 and 212 may each be provided with threadshaving a different pitch from the other. Such an arrangement allows boththe height and the angle between adjacent vertebral bodies to beadjusted simultaneously in a predetermined relationship when bothadjustment tools are turned together in unison. For example, proximalplug 210 may be provided with right-handed threads of a particular pitchwhile distal plug 212 may be provided with finer, left-handed threadshaving half the pitch of the proximal plug threads. In this embodiment,when both adjustment tools are turned together in a clockwise direction,both ends of UEC 200 expand at the same time but the proximal end 204expands at twice the rate of the distal end 206. This allows the surgeonto increase the height between adjacent vertebral bodies and at the sametime angle the bodies away from him or her. One or both of the tools maythen be turned individually to more finely adjust the height and anglebetween the vertebral bodies.

In some embodiments the above-described adjustment tools may be removedfrom UEC 200 before the surgical procedure is completed. In someembodiments the above adjustment tools may remain in place after theprocedure is completed.

In some embodiments, UEC 200 is 50 mm long, has an unexpanded diameterof 10 mm, and an expanded diameter of 14 mm. In other embodiments, theUEC may be configured to expand to about 11, 12, or 13 mm, or more than14 mm. In still other embodiments, the UEC may be configured withdimensions larger or smaller than these to conform to a particularanatomy or procedure.

Referring to FIGS. 16-20, a third embodiment of an exemplary UEC 300according to aspects of the disclosure is shown. FIG. 16 is aperspective view which shows details of UEC 300. UEC 300 includes aproximal end 304 and a distal end 306, and shares many of the samefeatures of previously described UECs 100 and 200, which are identifiedwith similar reference numerals.

Referring to FIG. 17, an exploded perspective view shows the individualcomponents of UEC 300. In this third embodiment, UEC 300 includes arectangular cage body 308, a proximal plug 310, a distal plug 312, aproximal plug adjustment tool 313, and a distal plug adjustment tool314. As in the previously described UEC 200, both plugs 310 and 312 arethreaded and tapered, and each end of cage body 308 is provided with aninwardly tapered and threaded bore configured to receive one of theplugs 310 or 312. Adjustment tools 313 and 314 are similar inconstruction and operation to the adjustment tools previously described(but not shown) in reference to UEC 200. Proximal plug 310 includes amating recess on its proximal end (not shown) configured to removablyreceive the splined distal end of proximal plug adjustment tool 313 forrotating proximal plug 310. Distal plug 312 includes a smaller matingrecess on its proximal end (not shown) configured to removably receivethe smaller splined distal end of distal plug adjustment tool 314 forrotating distal plug 312. Both proximal plug adjustment tool 313 andproximal plug 312 are provided with central bores that permit the distalend of distal plug adjustment tool 314 to pass therethrough, through thecenter of cage body 308, and partially into distal plug 312. In thisexemplary embodiment, the proximal ends of adjustment tools 313 and 314each have a hexagonally-shaped head that permits them to be turnedtogether in unison or individually (as previously described in relationto UEC 200), using wrench(es), socket(s) (not shown) and/or by hand.

As shown in FIGS. 16 and 17, cage body 308 includes eight longitudinallyextending beam portions 318, each separated from an adjacent beamportion 318 by a longitudinally extending gap 320. In other embodiments(not shown), the cage body may include fewer or more than eight beamportions, and/or beam portions having a different or varyingcross-section or shape. It can be seen that in this embodiment, four ofthe gaps 320 are formed through the middle of the four faces of cagebody 308, and the other four gaps 320 are formed along the corner edgesof cage body 308. Cage body 308 also includes eight circumferentiallyextending connector portions 322. The connector portions 322interconnect the ends of the beam portions 318. Circular apertures 321may be provided as shown between the ends of gaps 320 and the connectorportions 322 to relieve stress concentrations at those locations asconnector portions 322 flex. Four of the connector portions/flexures 322are located at the proximal end 304 of cage body 308 (across the corneredges of cage body 308), and the other four connector portions/flexures322 are located at the distal end 306 (across the distal end of thefaces of cage body 308.) The connector portions 322 located at theproximal end 304 are staggered in relation to the connector portions 322located at the distal end 306 such that each pair of adjacent beamportions 318 are connected at only one end by a connector portion 322.As with previously described embodiments, the beam portions 318 andconnector portions 322 form a continuous serpentine or repeatingS-shaped pattern. The beam portions 318 and or the connector portions322 are configured to resiliently flex to allow the cage body 308 toincrease in circumference when urged radially outward by plugs 310 and312. When plugs 310 and 312 are not urging cage body 308 radiallyoutward, the resiliency of beam portions 318 and or connector portions322 allows cage body 308 to return to its original reducedcircumference. It can be appreciated that as beam portions 318 and orconnector portions 322 flex outwardly, gaps 320 become wider at theiropen ends opposite connector portions 322. The outwardly facing surfacesof beam portions 318 may each be provided with one or more points orspikes 323 as shown, to permit cage body 308 to grip the end plates ofthe vertebral bodies. In this exemplary embodiment, spiked or knurledsurfaces are provided along the top and bottom of UEC 300 while the sidesurfaces are left smooth.

Referring to FIGS. 18 and 19, a side view and a side cross-sectionalview, respectively, of UEC 300 are shown. In operation, the proximal end304 of UEC 300 may be independently expanded by inserting proximal plugadjustment tool 313 into the mating recessed socket of proximal plug 310(as shown in FIG. 19) and turning it clockwise. Turning proximal plug310 clockwise causes the threaded ramped surfaces 332 of plug 310 totranslate inwardly (to the left in FIGS. 18 and 19) along the threadedramped surfaces 334 located along the inside of beam portions 318 andconnector portions 322 to cause these elements to flex and expandradially outward as previously described. This process may be reversedby turning proximal plug 310 counterclockwise, thereby allowing theproximal end 304 of UEC 300 to return to its non-expanded state.Similarly, the distal end 306 of UEC 300 may be independently expandedby inserting a tool such as a five-lobed socket (not shown) through thecentral bore 325 in proximal plug 310 until it engages with the proximalend of actuator 314, which is attached to distal plug 312. Turningdistal plug 312 counterclockwise (from the perspective of the proximalend) causes the threaded ramped surfaces 332 of plug 312 to translateinwardly (to the right in FIGS. 18 and 19) along the threaded rampedsurfaces 334 located along the inside of beam portions 318 and connectorportions 322 to cause these elements to flex and expand radially outwardas previously described. This process may be reversed by turning distalplug 312 clockwise, thereby allowing the distal end 306 of UEC 300 toreturn to its non-expanded state.

Referring to FIGS. 20A-20C, a series of sides views depicts theprogression from a fully retracted and a fully expanded UEC 300. In FIG.20A, cage body 308 is shown in a fully retracted position. In thisfigure, the height of each end of cage body 308 is labeled as 100% ofretracted cage height. In FIG. 20B, the proximal end 304 of cage body308 has been fully expanded while the distal end 306 remains fullyretracted. In this exemplary embodiment, each end is capable of beingexpanded to a height (and therefore also a width) that is 140% of thefully retracted height, as shown. In FIG. 20C, the distal end 306 hasalso been expanded by 40%.

In some embodiments, UEC 300 has a cage length of 50 mm, an unexpandedcage height of 10 mm, and an expanded cage height of 14 mm. The overalllength of UEC 300 with adjustment tools 313 and 314 in place and in theunexpanded state may be 75 mm. In other embodiments, the UEC may beconfigured to expand to about 11, 12, or 13 mm, or more than 14 mm. Instill other embodiments, the UEC may be configured with dimensionslarger or smaller than these to conform to a particular anatomy orprocedure. In some embodiments, the UEC can form an included anglebetween its top and bottom surfaces of at least 20 degrees.

Referring to FIG. 21, a fourth embodiment of an exemplary UEC 400according to aspects of the disclosure is shown. FIG. 21 is aperspective view which shows details of UEC 400. UEC 400 includes aproximal end 404, a distal end 406, cage body 408, proximal plug 410,distal plug 412, proximal plug adjusting tool 413, and distal plugadjusting tool 414. Other than cage body 408 having a circularcross-section rather than a square cross-section, UEC 400 is essentiallyidentical in construction and operation to previously described UEC 300.In other embodiments (not shown), the UEC may have a cross-sectiontransverse to the central longitudinal axis that is rectangular,trapezoidal, oval, elliptical or other shape.

Referring to FIGS. 22-25, a fifth embodiment of an exemplary UEC 500according to aspects of the disclosure is shown. FIG. 16 is aperspective view which shows details of UEC 500. UEC 500 includes aproximal end 504 and a distal end 506, and shares many of the samefeatures of previously described UECs 100-400, which are identified withsimilar reference numerals.

UEC 500 includes three components: a generally cylindrical, unitary cagebody 508; a proximal actuator screw 510; and a distal actuator screw512. The heads of actuator screws 510 and 512 may be referred to as plugmembers. Cage body 508 includes two longitudinal, off-center slots 550which each extend about three-quarters of the length of cage body 508,and emanate from opposite ends and opposite sides of cage body 508. Cagebody 508 is also provided with two transverse slots 552, each locatedadjacent to the closed end of one of the longitudinal slots 550. Eachtransverse slot 552 extends from the outer circumference of cage body508 and approaches the base of a longitudinal slot 550. Each of the twopairings of a longitudinal slot 550 with a transverse slot 552 defines acantilevered arm 554 that is connected with the remainder of the cagebody 508 by a living hinge 556 near the closed ends of the two slots 550and 552. Each living hinge 556 allows its associated arm 554 to flexoutwardly against a vertebral body.

The open ends of longitudinal slots 550 are outwardly tapered to receivethe enlarged, tapered heads of an actuator screw 510 or 512, as bestseen in FIG. 24. The opposite ends of actuator screws 510 and 512 extendthrough longitudinal slots 550 and thread into the opposite ends of cagebody 508. With this arrangement, each actuator screw 510 and 512 may beturned independently of the other, causing the screw to move axiallyrelative to bone cage 508. This axial movement causes the head of thescrew to urge the tapered tip of the associated arm 554 outward, orallowing it to flex back inward when the screw is turned in the oppositedirection. If both actuator screws 510 and 512 are turned in the samedirection the same amount, UEC 500 expands uniformly and increases theheight between adjacent vertebral bodies. If one of the two actuatorscrews 510 or 512 is turned more than the other, the surgeon is able tochange the angle between the vertebral bodies.

As best seen in FIG. 23, a slot 558 or other suitable feature may beprovided in the end of each actuator screw 510 and 512 at the oppositeend from the screw head. A hole 560 may also be provided through eachend of cage body 508 to allow access to each of the two slots 558. Thisarrangement allows both of the actuator screws 510 and 512 to be turnedfrom either end 504 and/or 506 of cage body 508.

Referring to FIGS. 26-28, an example implementation utilizing two UECs56 in tandem is shown. Each UEC 56 may be inserted as previouslydescribed in relation to FIGS. 1-3. In this implementation, UECs 56 areplaced non-parallel to one another. As best seen in FIG. 28, thisarrangement allows the surgeon to adjust the angle between the vertebraeabout two different axes, and also translate the vertebrae with respectto one another about another axis.

FIG. 29 is an oblique anterior view showing placement of an anteriorcolumn implant 56 on a vertebral body 52. In this implementation,implant 56 is placed laterally across the vertebral body 52, forward ofthe lateral midline. After adjustment of implant 56, its plugs are flushwith or recessed within the outer perimeter of the endplate of vertebralbody 52 so as not to impinge upon adjacent tissue.

Referring to FIG. 30, a human spine 76 is shown that exhibits scoliosis.According to aspects of the disclosure, dual UECs may be placed atvarious levels of the spine to treat the condition. For example, asingle UEC or pairs of UECs may be implanted at the levels depicted byreference numerals 78, 80, 82 and 84 shown in FIG. 30. By using theadjustments described above relative to FIG. 28, the curvature of thespine may be adjusted in three dimensions at these four levels to acorrect alignment, as shown in FIG. 31.

FIGS. 32A-32C are anterior, lateral and oblique views, respectively,showing adjacent vertebral bodies 50 and 52 having misalignments/unevenspacing.

FIGS. 33A-33C are anterior, lateral and oblique views, respectively,showing the vertebral bodies 50 and 52 of FIGS. 32A-32C with themisalignments/uneven spacing corrected according to aspects of thedisclosure.

The implants can be made of, for example, such materials as titanium, 64titanium, or an alloy thereof, 316 or 321 stainless steel,biodegradeable and biologically active materials, e.g. stem cells, andpolymers, such as semi-crystalline, high purity polymers comprised ofrepeating monomers of two ether groups and a ketone group, e.g.polyaryetheretherketone (PEEK)™, or Teflon™.

To prevent movement of proximal and distal plugs or actuators afterimplantation, in some implementations a biocompatible adhesive or threadlocking compound may be applied to one or more of the moving parts. Insome embodiments (not shown) a pin may be inserted radially or axiallybetween the plug/actuator and the cage body to lock the parts in placepost operatively. In some embodiments, a ratchet, spring loaded detent,or other locking mechanism may be provided for this purpose.

In general, as disclosed in the above embodiments, the cage body is cutwith openings at every other end of each slot, like a sine wave,allowing expansion when the center of the cage becomes occupied with acone or mandrill shaped unit. The cage body's series of alternatingslots allows the expansion to take place while keeping the outside ofthe UEC one single piece. The slots plus the teeth on the surface allowfor a solid grip on the bone surfaces and plenty of opportunities forgood bone ingrowth. Also, by allowing the surgeon to make one end of theUEC thicker than the other, the effects of the cone (mandrill)introduction vary from uniform to selective conduit expansion. The UECexpansion mechanism is adaptable to both fixed fusion and mobile ‘motionpreservation’ implants, with exteriors of the expanding implant persurgeon's choice (round, flat, custom, etc.) As such, in someimplementations, relative motion may be preserved between the vertebralbodies adjacent the implanted UEC(s). In other implementations, it maybe desirable to fuse the adjacent vertebral bodies around the implantedUEC(s).

To provide motion preservation between adjacent vertebrae, robustcompressible materials may be used between the UEC and one or both ofthe vertebral endplates, and/or one or more components of the UEC maycomprise such materials. These materials may replicate the loaddistributing and shock absorbing functions of the annulus and nucleus ofa natural disk. For example, in some embodiments the UEC may be providedwith tapered plugs made of a resilient polymer to allow the UEC tocompress and expand to accommodate relative motion of the adjacentvertebrae. Examples of biocompatible materials suitable for some UECembodiments include Bionate®, a thermoplastic polycarbonate-urethane(PCU) provided by DSM Biomedical in Exton, Pa., and ChronoFlex®, a PCUprovided by AdvanSource Biomaterials in Wilmington, Mass.

The UEC provides advantages over currently existing technology thatinclude correction of coronal plane deformity; introduction of interbodylordosis and early stabilization of the interbody space with rigiditythat is greater than present spacer devices. This early stability mayimprove post-operative pain, preclude the need for posterior implantsincluding pedicle screws, and improve the rate of successfularthrodesis. Importantly, the UEC provides improvement of spaceavailable for the neural elements while improving lordosis. Traditionalimplants are limited to spacer effects, as passive fillers of theintervertebral disc locations awaiting eventual fusion if and when bonegraft in and around the implant fuses. By expanding and morphing intothe calculated shape which physiologically corrects spine angulation,the UEC immediately fixes the spine in its proper, painless, functionalposition. As infused osteoinductive/osteoconductive bone graft materialsheal, the patient becomes well and the implant becomes inert andquiescent, embedded in bone, and no longer needed.

In some embodiments, the external surface of the UEC may be 3D printedto not only fit into the intervertebral space per se, but to match thesurface topography at each insertion location. In other words, a 3Dprinted endplate may be utilized, computer calculated to fit and expandthe disc space of the individual patient, resulting in both best‘goodness of fit’ for fusion, and improved axial skeletal alignment.

By creating to ‘maps’ that fit e.g. as a precisely congruent superiorand inferior surface to fit into a particular patients disc space, andplacing these UEC end plates on either side the novel UEC expansionmechanism, a patient's disc space AND overall spine alignment will beideally treated toward best fusion (or motion preservation) andalignment.

“Method of Surgery” instructions may recommend the surgeon and//orrobotic unit deploy expansion as programmed to insert the UEC into aparticular disc level of pathology, to achieve best results. Forexample, preoperative patient scans/films can predict ideal UEC surgeonuse, such as “turn Knob A a certain number of rotations clockwise,” tomaximize visible, palpable, and roentgenographic ‘Goodness of Fit’. Withthis approach, post activation, the UEC implant fits the location,entering at the predetermined best angle (in 3 axes) using theproprietary Method of Surgery and UEC insertion tools provided.

In some embodiments, the UEC may be coated with hydroxyapatite. In someembodiments, toothed or 400 μm beaded surfaces may be utilized topromote bony ingrowth. Inflatable chambers may be provided within theendplate that can expand after being implanted. This approach addressesthe 3-D congruence to proximate disc pathology. It can also allow forintervertebral arthrodesis or arthroplasty treatment and overallimproved spinal alignment, integrating the internal proprietaryexpansion with the variable external endplate shapes and their contents.UEC inflatable endplates of polymer may be employed, such as tinyvacuoles, “bubblewrap”, and multiple or singular bladder constructs. Ifa portion of the disk space were collapsed, that region could be aptlyelevated or expanded by the UEC endplate variation in material and/orinflation. The inflatable chambers may contain compressible gas (such asair,) granules as pharmacologics, and/or stem cells that are deliveredvia liquids. In cases where the UEC is compressible or force absorbing,the material and/or chamber could be used as a cushion or to‘selectively direct and protect chondrocytes’ toward improvement ofexisting pathophysiology via best drug use or regeneration.

The ‘preparation’ of the UEC insertion site will vary per surgeon. Insome implementations, an arthroscopic burr may be advisable for removing0.5 mm of cortical bone along with all aberrant disc contents underdigital arthroscopic camera control. In other implementations, thesurgeon may just carefully curette the intervertebral space to ‘clean itout’ in preparation for the UEC implant insertion.

The UEC may be inserted directly into the insertion site, or may beinserted through proprietary or commercially available insertion tube.The insertion tube typically will have a blunt distal tip so that it canbe inserted through an incision without causing tissue damage. The tubecan be used with or without additional tissue retractors. The UEC may bepreloaded into the insertion tube, or placed into the tube after thetube has been introduced into the insertion site. A pusher rod or otherdevice may be utilized to deploy the UEC from the insertion tube intothe insertion site. In some procedures, the placement of the UEC may bearthroscopically assisted.

Note that regardless of the endplate preparation, in the deformed,aging, pathologic spine there will be pathology to correct. According tovarious aspects of the present disclosure, the UECs provided herein mayaccomplish this in several ways as pertains to the external implantcomposition. For example, the UEC can expand as an externally threadedconduit, either uniformly end to end resulting in same diameters at eachend post-operatively (such as 40% overall expansion), or precisely ateither end, thus creating an overall conical albeit expanded UEC. Also,the UEC can be flat superiorly and inferiorly as shown in the abovedrawings, thus more likely matching the rather flat vertebral body endplates. However, according to further aspects of the present disclosure,special care should be taken to consider both the peripheral end plateboney rim as thicker more prominent cortical bone at the vertebral endplates with a sunken or concave thinner interior (thus subject topotential subsidence). The UEC MOS (Method of Surgery) contemplatedherein considers the preoperative findings (e.g. MRI, 3D CT scan,X-rays) to integrate information on bone density, specific disc spaceand longitudinal spine anatomy, topography and alignment.

The various expanding cages disclosed herein and variations thereof arenot limited to use in the spinal column but may be used between otherbone segments throughout the human or animal body. For example, a UECcan be used during arthrodesis of a metatarsal joint. The UEC can aid insetting the orientation of the toe to a desired angle before fusion ofthe apposing bone segments occurs. Similarly, a UEC may be utilized inthe knee, elbow or other body joints, or between two or more bonesegments that have been fractured by trauma.

According to various aspects of the disclosure:

1) the UEC corrects spine surgical pathology both locally via horizontal(disc) and longitudinal vertical axial (scoliotic/kyphotic) spinedeformity improvements.

2) the UEC is applicable cervical through lumbar for

-   -   A) arthrodesis (fusion) or    -   B) arthroplasty (motion preservation)    -   C) drug/cell therapy delivery

3) the UEC can expand uniformly throughout implant length, and/or expandonly proximally (toward the surgical incision) or distally, thusenabling clinical adjustments favorable to spine diseased or injuredpatients for local and overall spondylopathies.

4) the UEC can be surgically inserted via outpatient MIS (MinimallyInvasive—outpatient Surgery) as safe, efficacious implants “doing noharm” applying advantages from

-   -   A) materials thicknesses for height differentials or    -   B) expansion adjustments surgically controlled (before/during or        after implantation) or via prefabricated portals or        injections—programing implant ‘mapped’ corrections using    -   C) polymers durometrically calculated with variable        compressions, permanent or biodegradable activations at will.    -   D) inflation of the implant as via UEC surface chambers or        bladder(s).    -   E) adding endplate biologics, foam, or other adaptables for best        results.    -   F) UEC expansion can adapt to expand variable external surface        parameters including flat, round, or customized external        maximally congruent surfaces to interface as with proximate        endplates.

5) Delivery either via UEC materials per se (eluding substances—cells orpharmacologics) or through extrusion from a UEC container or deliveryvesicle/depot/chamber/portal will enable not only immediate surgicallycorrection but long term enhanced bone in growth and local/generaltherapeutic and/or regenerative clinical benefits.

While the disclosure has been described in connection with exampleembodiments, it is to be understood that the disclosure is not limitedto the disclosed embodiments and alternatives as set forth above, but onthe contrary is intended to cover various modifications and equivalentarrangements included within the claim scope.

What is claimed as the invention is:
 1. An expandable medical implantcomprising: an implantable cage body having a proximal end provided witha first tapered portion and a distal end provided with a second taperedportion, the first and second tapered portions being tapered in oppositedirections, the cage body further having a longitudinal axis extendingbetween the proximal end and the distal end of the cage body; at leastone proximal flexure at least partially located adjacent to the proximalend of the cage body and configured to allow a circumference of thedistal end of the cage body to resiliently expand; at least one distalflexure at least partially located adjacent to the distal end of thecage body and configured to allow a circumference of the proximal end ofthe cage body to resiliently expand; a proximal plug member having atapered portion configured to mate with the first tapered portion of theproximal end of the cage body, the proximal plug member being configuredto move longitudinally relative to the cage body from a first positionto a second position such that the at least one distal flexure moves andthe circumference of the proximal end of the cage body resilientlyexpands, and from the second position to the first position such thatthe circumference of the proximal end resiliently contracts; a distalplug member having a tapered portion configured to mate with the secondtapered portion of the distal end of the cage body, the distal plugmember being configured to move longitudinally relative to the cage bodyfrom a third position to a fourth position such that the at least oneproximal flexure moves and the circumference of the distal end of thecage body resiliently expands, and from the fourth position to the thirdposition such that the circumference of the distal end resilientlycontracts; a first adjustment member configured to be coupled to atleast the proximal plug member such that when the first adjustmentmember is rotated, the proximal plug member is caused to movelongitudinally; and a second adjustment member configured to be coupledto the distal plug member such that when the second adjustment member isrotated, the distal plug member is caused to move longitudinally,thereby allowing the proximal and the distal ends of the cage body to beexpanded and contracted independent from one another, wherein the firstand the second adjustment members are independently rotatable andoperable from a single end of the cage body.
 2. The expandable medicalimplant of claim 1, wherein the first tapered portion comprises a firsttapered bore at the proximal end configured to slidably receive theproximal plug member, and the second tapered portion comprises a secondtapered bore at the distal end configured to slidably receive the distalplug member.
 3. The expandable medical implant of claim 2, wherein thefirst tapered bore threadably engages the proximal plug member such thatwhen the proximal plug member is rotated relative to the cage body, theproximal plug member advances in a longitudinal direction relative tothe cage body, and wherein the second tapered bore threadably engagesthe distal plug member such that when the distal plug member is rotatedrelative to the cage body, the distal plug member advances in alongitudinal direction relative to the cage body.
 4. The expandablemedical implant of claim 1, wherein the at least one proximal flexurecomprises a generally circular and open ended aperture and a pair ofgenerally flexible beam portions extending longitudinally from theaperture.
 5. The expandable medical implant of claim 1, wherein the atleast one proximal flexure comprises a pair of longitudinally extendingbeam portions separated by a longitudinally extending gap, wherein theat least one proximal flexure further comprises a connector portioninterconnecting proximal ends of the beam portions.
 6. The expandablemedical implant of claim 1, wherein the at least one proximal flexurecomprises a plurality of circumferentially spaced proximal flexures, andwherein the at least one distal flexure comprises a plurality ofcircumferentially spaced distal flexures.
 7. The expandable medicalimplant of claim 6, wherein the plurality of proximal flexures arerotationally staggered from the plurality of distal flexures.
 8. Theexpandable medical implant of claim 7, wherein each of the proximalflexures comprises a pair of longitudinally extending beam portionsseparated by a longitudinally extending gap and bridged together by aconnector portion interconnecting only proximal ends of the beamportions, wherein each of the distal flexures comprises a pair oflongitudinally extending beam portions separated by a longitudinallyextending gap and bridged together by a connector portioninterconnecting only distal ends of the beam portions, and wherein eachof the proximal flexures shares a beam portion with two of the distalflexures that are adjacent to each proximal flexure, thereby forming acontinuous serpentine pattern along the cage body.
 9. The expandablemedical implant of claim 1, wherein the first and the second adjustmentmembers each have knobs axially spaced but adjacent to one another suchthat the knobs may alternately be rotated in unison or individually. 10.The expandable medical implant of claim 1, wherein at least one of thefirst and the second adjustment members has a keyed end configured toslidably mate and rotationally couple with its associated plug membersuch that the at least one adjustment member can be removed from theexpandable medical implant.
 11. The expandable medical implant of claim1, wherein the cage body has a square cross-section transverse to thelongitudinal axis.
 12. The expandable medical implant of claim 1,wherein the cage body has a circular cross-section transverse to thelongitudinal axis.
 13. A method of distracting adjacent bone segmentshaving opposing surfaces, the method comprising: inserting theexpandable medical implant of claim 1 between the opposing surfaces;moving the proximal and the distal plug members longitudinally andindependently from one another such that the proximal and the distalends of the cage body expand independently to alter the distance and theangle between the opposing surfaces of the bone segments.
 14. The methodof claim 13, further comprising; removing at least one adjustment memberfrom the medical implant after the adjustment member has been used tomove at least one of the proximal and distal plug members.
 15. Themethod of claim 14, wherein the bone segments are adjacent vertebrae,and the opposing surfaces are end plates of the adjacent vertebrae.